> "If her being Dx'ed with BPD, how does not raging at the son fit"

well...

first law of diagnoses: more people meet NOS than 'typical' anything.

it is important to remember that first and foremost your sister is a PERSON and not a typical instance of any diagnostic category.

if you think that she could use some help then it would be nice if you could try and find some for her...

otherwise... pays to be wary of psychology student syndrome (which tends to hang around after graduation) where bachelors students and young graduates like to go around putting the people they know into little categorical boxes because... they can.

further study is quite often the antidote.

you make it sound like if there is a diagnostic category that lists her behaviour in symptom lists then there is no trouble explaining it. but a diagnostic category just is a behavioural symptom list so diagnostic cateogories don't explain why anybody has the behavioural symptoms they do. as such any 'explanation' that is given by attaching a label to someone... is a pseudoexplanation. it hoodwinks insurance companies and consumers and is oftentimes seductive to others as well.

if you think your sister could benefit from professional help then then maybe you could talk to her about that?